The present invention relates generally to fire stopping devices and, more particularly, to a fire stopping device including a flexible and conformable shell filled with an intumescent material which serves to form a fire barrier in the event of a fire.
One mechanism by which fire may spread from one compartment of a structure to another is through passages or openings, often referred to as through-penetrations, in the floors and walls. Such openings include, for example, cable access holes through which signal and power transmission cables pass.
Current methods used to prevent the spread of fire and passage of smoke through such openings include cutting two intumescent sheets to follow the contour of the penetrating cables and providing a bead of moldable intumescent putty along the perimeter of each sheet. While this technique is generally satisfactory for resisting the spread of fire and preventing the passage of smoke from one compartment to another, installation is labor intensive and time consuming. In addition, fire stops fabricated in this manner do not lend themselves to repeated re-entry.
Techniques for fire stopping through-penetrations are known in the prior art. The U.S. patent to Robertson et al. U.S. Pat. No. 5,155,957 for example, discloses a fire safety device for closing through-holes in floors and walls which includes a section of conduit, a cup-shaped retainer spaced from the outside surface of the conduit section so as to define an annular space which contains an intumescent material, and a floating floor below the intumescent material which, in the event of fire, moves inwardly to occupy the interior space previously occupied by the conduit section.
The U.S. patent to Navarro et al. U.S. Pat. No. 5,887,395 discloses a fire stop sleeve including a layer of intumescent composite forming a moldable putty with a restraining layer for wrapping around a pipe extending through a floor or the like, and further including a plurality of bendable tabs for depression into the wrapped layer to hold the restraining layer in position during installation.
The U.S. patent to Bailey U.S. Pat. No. 5,032,447 discloses a fire barrier material for use in building construction comprising a sandwich structure having first and second outside layers comprising corrugated high temperature resistant metal and at least one intermediate layer comprising a flame retardant fibrous material, wherein the corrugations are positioned on the outside layers in an array which enables the barrier material to be folded in a direction substantially perpendicular to the corrugations.
In addition, various bag-like devices for fire stopping through-penetrations are available commercially. Each of these prior devices or techniques, however, suffer from certain drawbacks or shortcomings. Accordingly, there exists a need in the industry for a pre-fabricated fire stopping device for fire stopping through penetrations which has improved fire stopping characteristics, is cost effective, and is easy to install.
The present invention provides a fire stopping device including a containment shell and a heat rupturable element which define an interior chamber, and an intumescent filler material arranged in the interior chamber. The containment shell is formed of a fire resistant material capable of retaining the intumescent material after the rupturable element fails. In addition, the heat rupturable element is designed to fail at a force which is lower than the intumescent filler material expansion force at the activation temperature of the intumescent filler material. In this manner, when the intumescent filler material reaches its activation temperature, it expands with a force greater than the strength of the rupture element, thereby causing the rupture element to fail. Thus, expansion of the intumescent filler material takes place in a controlled manner via the rupture element.
In one aspect of the invention, the rupturable element fails at a rupture temperature and the intumescent filler material intumesces at an activation temperature, and the rupture temperature is lower than the activation temperature. In another aspect, the containment shell includes a seam, and the rupturable element is a fastener which joins the seam. The fastener may be an adhesive, a stitched thread, a mechanical fastener, or another conventional fastener.
The containment shell may include separate top and bottom sheets having adjacent peripheral edges joined together to define the seam. The top and bottom sheets may be formed of the same fire resistant material or different materials. In one embodiment, the top and bottom sheets are a mat of intumescent material which may be laminated with an outer cover layer to enclose and seal the intumescent mat, thereby improving the handleability of the device.
In another aspect of the invention, the containment shell has opposed top and bottom major surfaces, and the rupturable element forms a portion of the top surface. In another aspect of the invention, the rupturable element is a seam arranged in the top surface of the containment shell. In yet another aspect, the rupturable element comprises the entire top surface of the containment shell.
In another aspect of the invention, the fire stopping device includes a sheet of infrared radiation blocking material or endothermic material provided on the inner surface of the containment shell adjacent the interior chamber. In a specific embodiment of the invention, the device includes both a sheet of infrared radiation blocking material and a sheet of endothermic material, and the sheet of endothermic material is arranged on the inner surface of the infrared radiation blocking material. In another embodiment, the fire stopping device further includes a sheet of intumescent material arranged adjacent the infrared radiation blocking material.
In yet another aspect of the invention, the intumescent filler material comprises a plurality of discrete particles. The intumescent filler material may comprise a mixture of intumescent material, insulating material, and endothermic material. Alternately, the filler material may be a moldable intumescent putty.